feat: relocate import tools into studio and harden catalog/furnidata integrity

- Move /admin/import/* tools under /admin/studio/* and add studio nav, layout and tabs
- Add shared catalog maintenance panel plus a /admin/studio/maintenance tab
- Make furnidata reconciliation overwrite conflicting entries with the
  DB-authoritative items_base classname/id (surfaced via fixedConflicts)
- Add furnidata_translate_enabled setting to skip the heavy localized
  furnidata build during import (manual build-languages still forces it)
- Update staff smoke contract test for the studio hub

src/app/admin/studio/sync/page.tsx

@@ -0,0 +1,26 @@
+import { redirect } from "next/navigation";
+import { SyncAllClient } from "@/app/admin/import/sync/sync-all-client";
+import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
+
+export default async function StudioSyncPage(_props: {
+	params: Promise<{ locale: string }>;
+}) {
+	const { session, permissions } = await getAdminContext();
+	if (!canAccess(permissions, PERMS.ASSETS_IMPORT, session.user.rank)) {
+		redirect("/admin");
+	}
+	return (
+		<div className="space-y-6 p-4">
+			<div>
+				<h1 className="text-2xl font-bold tracking-tight">Sync All Sources</h1>
+				<p className="mt-1 text-muted-foreground">
+					Scan all configured clone sources and automatically import any
+					furniture that is not yet present in your hotel. Missing .nitro files,
+					icons, database entries, catalog items, and FurnitureData.json will be
+					added automatically.
+				</p>
+			</div>
+			<SyncAllClient />
+		</div>
+	);
+}